The present invention relates to the field of electronic controls and more specifically to an electronic power control system for cooktop heating elements.
Conventional controls for electric cooktops utilize so-called “infinite switches.” The infinite switch comprises a bimetal switch to control an electric heating element. Current flowing in the bimetal switch causes it to physically move through a process of heating and cooling. This movement causes the switch contacts to open and close, thereby, controlling the power applied to the heating element.
The infinite switch uses pulse width modulation to control the power output, and thus the temperature of the heating element. Rotation of the infinite switch changes the relationship of the closed and open times or duty cycle. As the switch is rotated to a higher setting the contacts remain closed for a longer period of time, raising the heating element temperature. Conversely, rotating the switch to a lower setting causes the contacts to remain closed for a shorter period of time, lowering the heating element temperature.
Recently, electronic controls have been increasing in popularity. Electronic controls are capable of providing a more precise level of heating. Further, associated digital controls are easier to read than an analog dial, allowing the quick setting of desired heat levels. Electronic controls are also capable of providing advanced features, such as a safety lockout.
Analog controls remain desirable because their associated rotational control knobs are often easier to manipulate and more convenient for the user than the button-type controls conventionally associated with electronic controls. Likewise, using a duty cycle to control the level of heating remains desirable, because it allows the heating elements to provide very low levels of heat, including levels suitable for warming operations.